Body mass index (BMI) may not measure obesity accurately

BMI is a highly insensitive measure of obesity prone to under-diagnosis, while direct fat measurements are superior because they show distribution of body fat.

In a single-center study, 66% of patients classified as obese on the basis of DEXA scanning had BMI values in the non-obese range, according to Eric Braverman, MD, of New York Presbyterian Hospital/Weill Cornell Medical Center.

Among more than 1,000 patients, 56% were obese according to the DEXA results, versus 20% using the standard BMI-based definitions.

Scoffing at BMI as the “baloney mass index,” Braverman said it’s “very likely that obesity is a much bigger epidemic than the 300 million people acknowledged by the World Health Organization.”

BMI is just a mathematical equation based solely on height and weight that is too general for diagnosing anything, especially in such an exacting field of clinicians.

Braverman said that if any endocrinologists rely on math to calculate thyroid stimulating hormone, he would be laughed at.

DEXA scans, on the other hand, provide a direct measurement of body fat percentage and can spot fat exactly, in every part of the body.

It’s particularly effective, Braverman said, for that part of the population that is known as “thin-but-unfit.”

Their condition is known as normal-weight obesity, in which the BMI is low but they have a high percentage of body fat, especially compared with more favorable tissue like muscle.

These patients are at higher risk of dyslipidemia, as well as hypertension among men and cardiovascular disease among women.

The researchers found that DEXA identified 56% of patients as obese while BMI identified 20% as such.

Among those classified as obese by DEXA, only 34% were classified as obese by BMI and 5% of patients identified as obese by BMI actually weren’t obese according to DEXA scans.

These individuals were muscular and large, so they look like they’re high weight but they really had high muscle mass.

This means that we may have more health problems, as individuals are delaying treatment because they don’t think they’re obese and think they’re thin and ‘just a little flabby.